Suggest ClusterSharding hasn't been started in log message (#25177)

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ShardCoordinator.scala

@@ -10,7 +10,6 @@ import scala.collection.immutable
 import scala.concurrent.Future
 import scala.concurrent.duration._
 import scala.util.Success
-
 import akka.actor._
 import akka.actor.DeadLetterSuppression
 import akka.cluster.Cluster
@@ -953,7 +952,7 @@ class DDataShardCoordinator(typeName: String, settings: ClusterShardingSettings,
 
     case GetFailure(CoordinatorStateKey, _) ⇒
       log.error(
-        "The ShardCoordinator was unable to get an initial state within 'waiting-for-state-timeout': {} millis (retrying)",
+        "The ShardCoordinator was unable to get an initial state within 'waiting-for-state-timeout': {} millis (retrying). Has ClusterSharding been started on all nodes?",
         readMajority.timeout.toMillis)
       // repeat until GetSuccess
       getCoordinatorState()

akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardingIncorrectSetupSpec.scala

@@ -0,0 +1,63 @@
+/**
+ * Copyright (C) 2017-2018 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package akka.cluster.sharding
+
+import akka.cluster.MultiNodeClusterSpec
+import akka.remote.testkit.{ MultiNodeConfig, MultiNodeSpec }
+import akka.testkit._
+import com.typesafe.config.ConfigFactory
+
+object ClusterShardingIncorrectSetupSpecConfig extends MultiNodeConfig {
+  val first = role("first")
+  val second = role("second")
+
+  val commonConfig = ConfigFactory.parseString(
+    """
+      akka.loglevel = INFO
+      akka.cluster.sharding {
+         waiting-for-state-timeout = 100ms
+      }
+    """.stripMargin)
+
+  commonConfig(commonConfig.withFallback(MultiNodeClusterSpec.clusterConfig))
+}
+
+class ClusterShardingIncorrectSetupMultiJvmNode1 extends ClusterShardingIncorrectSetupSpec
+class ClusterShardingIncorrectSetupMultiJvmNode2 extends ClusterShardingIncorrectSetupSpec
+
+object ClusterShardingIncorrectSetupSpec {
+  val extractEntityId: ShardRegion.ExtractEntityId = {
+    case id: Int ⇒ (id.toString, id)
+  }
+
+  val extractShardId: ShardRegion.ExtractShardId = {
+    case id: Int ⇒ id.toString
+  }
+}
+
+abstract class ClusterShardingIncorrectSetupSpec extends MultiNodeSpec(ClusterShardingIncorrectSetupSpecConfig) with MultiNodeClusterSpec with ImplicitSender {
+
+  import ClusterShardingIncorrectSetupSpec._
+  import ClusterShardingIncorrectSetupSpecConfig._
+
+  "Cluster sharding" must {
+    "log useful error message if sharding not started" in {
+      awaitClusterUp(roles: _*)
+      enterBarrier("cluster-up")
+      runOn(first) {
+        EventFilter.error(pattern = """Has ClusterSharding been started on all nodes?""").intercept {
+          ClusterSharding(system).start(
+            typeName = "Entity",
+            entityProps = TestActors.echoActorProps,
+            settings = ClusterShardingSettings(system),
+            extractEntityId = extractEntityId,
+            extractShardId = extractShardId)
+        }
+        enterBarrier("helpful error message logged")
+      }
+    }
+  }
+}
+